New endophytic isolates of Muscodor albus, a volatile-antibiotic-producing fungus

Muscodor albus, an endophytic fungus originally isolated from Cinnamomum zeylanicum, produces a mixture of volatile organic compounds (VOCs) in culture and its spectrum of antimicrobial activity is broad. Using the original isolate of M. albus as a selection tool, it has been possible to find other culturally and biochemically unique wild-type isolates of this organism existing as endophytes in a variety of other plant species, including Grevillea pterifolia (fern-leafed grevillea), Kennedia nigriscans (snake vine) and Terminalia prostrata (nanka bakarra) growing in the northern reaches of the Northern Territory of Australia. Interestingly, none of the new isolates had a culture morphology that was identical to the original isolate, nevertheless each possessed hyphal characteristics that resembled that isolate. Furthermore, their ITS-5.8S rDNA sequences were 96-99 % identical to that of M. albus and the isolates were considered M. albus on the basis of the DNA sequence data. However, the VOCs produced by these new isolates greatly differed in quality from the original strain by virtue of the production of naphthalene, naphthalene, 1,1'-oxybis-, and one or more other compounds. In bioassays with a range of test micro-organisms, including fungi and bacteria, each isolate possessed biological activity but the range of activity was great. Artificial mixtures of some of the VOCs mimicked the effects of the VOCs of the fungus. The value of these observations to the biology and practical uses of M. albus in agriculture and other applications is discussed.